The present invention relates to a throttle apparatus for an engine for electrically performing control for a throttle valve angular position by means of a throttle actuator.
In the recent years, according to advancing of an electronic control for an engine, there has been proposed a technology for controlling an angular position of a throttle valve by detecting a position of an accelerator pedal (accelerator operating rate) by means of an accelerator position sensor and driving a throttle actuator (DC motor, stepping motor and so forth) on the basis of an accelerator position sensor signal and a control signal, such as, a traction control signal and so forth.
Recently, in a system for electrically controlling the angular position of the throttle valve as set forth above, there have been proposed technologies, in which an angular position of the throttle valve at OFF position of an engine key (in other words, while an electric power is not supplied to a throttle actuating motor: initial throttle valve angular position) is set at an angle greater than a minimum angle of the throttle angular position (normally, an idling opening of the throttle valve in a steady state of the engine after warming up) in a control range of the throttle valve angular position, within which the throttle valve angular position is controlled by means of the throttle actuating motor (see PCT National Publication No. 2-500677(1990), Japanese Patent Application Laid-Open No. 3-271528(1991), Japanese Patent Application Laid-Open No. 4-203219(1992), for example).
One reason why the initial opening is set at the foregoing position, is to satisfy a demand for preventing sticking of the throttle valve due to deposition of a viscosity matter, ice or the like. In addition, the initial opening set forth above is intended to assure self-travel (limp home) even upon failure of a throttle control system, and to certainly provide sufficient air flow rate for preventing the engine from stalling.
An initial opening setting mechanism (occasionally referred to as default mechanism) sets a position (close to a fully closed position of the throttle valve) where a spring force of a return spring biasing the throttle valve in a closing direction and a spring force of an initial opening spring for biasing the throttle valve in an opening direction, are balanced, as the initial opening, in principle.
In the throttle apparatus having the initial opening setting mechanism of the type set forth above, when an engine key is turned-on, for example, the throttle valve is mechanically driven from the foregoing initial opening to the minimum point of motor control (position contacting with an adjusting screw) by means of the throttle actuating motor. Thereafter, an angular position of the throttle valve is controlled at a position corresponding to an engine coolant temperature and so forth.
In an engine control portion, sensors, such as an air flow sensor, a throttle position sensor and so forth, have to be provided in an air intake system. When mechanical parts, such as the throttle actuator, gear and so forth are mounted in addition to the foregoing sensors, number of parts can be increased. On the other hand, a space in the engine room is limited.
In an electronically controlled throttle apparatus (hereinafter occasionally referred to as xe2x80x9celectronic throttle apparatusxe2x80x9d), a technology for aggregating and rationalization of initial opening setting mechanism, such as sensor parts, actuator parts and so forth has been held immature. Therefore, optimal installation technology has been strongly demanded. Particularly, it is typical to provide a body of the air flow sensor and the throttle body, separately. When such prior art is applied to the electronic throttle apparatus, electronic control parts and mechanical parts, such as sensor parts, actuators and so forth, are straggled to increase work load in assembling operation and wiring operation in the case where the throttle apparatus is installed in the engine room. Also, it is not easy to avoid interference between the throttle apparatus and other parts due to limitation of the space in the engine room.
The present invention has been worked out in view of the drawbacks set forth above.
An object of the present invention is to provide an electronic throttle apparatus which permits aggregating of various parts and rationalization of installation, and can simplify assembling operation and wiring operation to an engine room for rationalization of an installation space.
Another object of the present invention is to guarantee stable operation of a throttle mechanism by a motor control and to enhance accuracy.
The present invention is generally constructed as follows.
At first, the present invention is directed to a mounting technology of a throttle actuating motor, a throttle position sensor and an air flow sensor.
In the first aspect of the present invention, the throttle actuating motor, the throttle position sensor detecting a throttle valve angle, and the air flow sensor located on upstream of the throttle valve and measuring an intake air flow rate are mounted on the throttle body.
With the construction of the foregoing first aspect of the present invention, parts for electronic control can be concentrically arranged on the throttle body. On the other hand, operation for assembling the air flow sensor-body and the throttle body which are otherwise formed separately, in the air intake passage, can be eliminated, so that assembling operation can be completed by single assembling operation of the throttle apparatus. On the other hand, the various external electric wiring such as the sensor output lead wire, the power source wiring, the grounding wiring and so forth can be aggregated on the closer side to the throttle body. Thus, enhancement of efficiency of the wiring connecting operation can be achieved.
In the second aspect of the present invention, in addition to the construction set forth in the first aspect of the invention, the throttle body can be designed to orient an air passage transversely when the throttle body is installed within an engine room, and formed with a casing portion of the motor and a mounting portion of the air flow sensor on an upper surface to be located on an upper side upon installation, among external walls thereof.
With the construction of the second aspect of the present invention as set forth above, the air flow sensor as an accessory of the throttle apparatus, can be taken out from the throttle body independently and easily, even after installation of the throttle body within the engine room for enhancing convenience in inspection, maintenance and exchanging. On the other hand, since the motor casing portion extends over the upper surface of the throttle body, a step is formed between the motor casing portion and the upper surface of the remaining throttle body. A space defined by the step can be effectively utilized as an installation space of the air flow sensor. Therefore, wasting of space around the throttle body can be eliminated to increase density of concentration in mounting of the parts.
In the third aspect of the present invention, in addition to the construction set forth in the first aspect of the invention, directionality of connector terminals for electrical connection with external electric wiring of the throttle actuating motor, the throttle position sensor and the air flow sensor can be matched with each other.
Various external electric wiring (sensor output line, the sensor power line, the motor line and so forth) can be lead from the engine control unit to the throttle body. Since the connector terminals of electrical connection for the external electrical wiring of the throttle actuating motor, the throttle position sensor, the air flow sensor are matched directionality so that various electric wiring are not required to be lead from different directions to make operation for establishing electrical connection quite simple.
As an optimum embodiment, according to the fourth aspect of the present invention, the throttle body may be designed to orient an air passage transversely when the throttle body is installed within an engine room, and the throttle actuating motor and a circuit module of the air flow sensor being mounted on an upper surface to be located on an upper side upon installation, among external walls the throttle body, directionality of connector terminals for electrical connection with external electric wiring of the throttle actuating motor and the air flow sensor may be matched with each other, and the throttle position sensor may be arranged on a side surface of an external wall of the throttle body on the side, toward which the connector terminals for electrical connection with external electric wiring of the throttle actuating motor and the air flow sensor are directed, and directionality of a connector terminal for electrical connection with an external electrical wiring of the throttle position sensor being consistent with those of the connector terminals for electrical connection with external electric wiring of the throttle actuating motor and the air flow sensor. With this construction, the effects to be achieved in the foregoing second and third aspects of the present invention can equally achieved.
Also, according to the fifth aspect of the present invention, a throttle body includes a throttle valve and a throttle actuating motor, and a throttle position sensor mounted on an external wall of the throttle body, and directionality of a connector terminal for electrical connection of the throttle position sensor with an external electric wiring and a connector terminal for electrical connection of the throttle actuating motor are matched with each other. Thus, connecting operation of various electric wiring can be further simplified.
In the sixth aspect of the present invention, in addition to the construction employed in the foregoing fifth aspect of the present invention, a connector terminal for electrical connection of the throttle position sensor with an external electric wiring and a connector terminal for electrical connection of the throttle actuating motor are aggregatingly housed within a sensor casing with matching directionality thereof, and a mounting portion of the throttle position sensor being covered with a resin cover, and a female connector casing for introducing the aggregated connector terminals within the sensor casing, is formed in a part of the resin cover.
With the construction in the foregoing sixth aspect of the present invention, since the connector terminals of the throttle position sensor and the connector terminals of the throttle actuating motor may be aggregatingly provided in the female type connector casing provided in the sensor cover of the synthetic resin which covers the sensor casing, the connector portion (connector casing) can be concentrated. Correspondingly, the external electric wiring of the throttle position sensor and the external electric wiring of the throttle actuating motor can be aggregated to be concentrically terminated to the connector portion (male connector casing). Thus, connecting operation of the electric wiring can be performed by simply mating the male connector and the female connector.
It is expected that the different shapes of the connector casings of the electrical wiring are used in respective of makers. Even in such case, the sensor casing of the throttle position sensor may be used as is and it is only required to exchange the resin sensor cover to one having the connector casing adapted to the shape of the male connector on the electric wiring. Therefore, the throttle position sensor may be common to respective makers to improve compatibility of the parts.
In addition to the foregoing sixth aspect, in which the connector terminal for electrical connection of the throttle position sensor with an external electric wiring and the connector terminal for electrical connection of the throttle actuating motor are aggregatingly housed within a sensor casing with matching directionality thereof, in consideration of convenience of wiring operation within the throttle body of the terminal directly mounted on the throttle actuating motor and the connector terminal, a construction, in which a motor casing of the throttle actuating motor is integrally formed with the throttle body, a power input terminal directly mounted on the throttle actuating motor housed within the motor casing, is located in a mounting portion of the throttle position sensor, and a rear end of the connector terminal for electrical connection of the throttle actuating motor is connected to the power input terminal directly mounted on the throttle actuating motor via a connector with a lead wire, has been proposed as the seventh aspect of the present invention.
As the eighth aspect of the present invention, as an alternative of the seventh aspect of the present invention as set forth above, the throttle apparatus for an engine comprises:
a throttle body including a throttle valve and a throttle actuating motor; and
a throttle position sensor mounted on an external wall of the throttle body,
a connector terminal for electrical connection of the throttle position sensor with an external electric wiring and a connector terminal for electrical connection of the throttle actuating motor being aggregatingly housed on a surface side of a sensor casing,
a connector terminal to be connected with a power input terminal directly mounted on the throttle actuating motor, being arranged on a backside of the sensor casing,
a motor casing of the throttle actuating motor being integrally formed with the throttle body,
a power input terminal directly mounted on the throttle actuating motor housed within the motor casing, being located in a mounting portion of the throttle position sensor; and
the power input terminal directly mounted on the throttle actuating motor and the connector terminal provided on back side of the sensor casing having a terminal structure for direct engagement upon installation of the sensor casing on an external wall of the throttle body.
With the construction set forth above, the external electric wiring to be connected to the throttle position sensor and the throttle actuating motor within the engine room can be connected with a single connector portion on (the surface side of the casing of the throttle position sensor) of the throttle body. Also, even when the throttle position sensor 32 is mounted on the throttle body 1 before installation within the engine room, the connector terminal corresponding to the throttle actuating motor provided on the backside of the sensor casing can be mated with the power input terminal directly mounted on the throttle actuating motor within the sensor mounting space, at one action to successfully simplify connection of electrical wiring on the inside or outside of the throttle body.
In the ninth aspect of the present invention, similar to the foregoing eighth aspect of the invention, there has been proposed a construction, in which a connector terminal to be connected with a power input terminal directly mounted on the throttle actuating motor, being arranged on a backside of the sensor casing, and the power input terminal directly mounted on the throttle actuating motor and the connector terminal provided on back side of the sensor casing being directly (without lead wire) connected via a sleeve joint.
Even with the construction set forth above, the similar function and effect to the achieved by the foregoing eighth aspect can be achieved.
In consideration of facilitating of mounting the following construction is proposed for the throttle actuating motor in the tenth aspect of the present invention, that a throttle apparatus for an engine comprises:
a throttle valve and a throttle actuating motor mounted on a throttle body of an air intake system of the engine;
a motor casing for the throttle actuating motor being formed integrally with the throttle body, which motor casing defines a tapered hole gradually increasing a diameter from a bottom side end to an opening side end and has a diameter greater than an outer diameter of the throttle actuating motor,
an end cover with a flange being provided on the throttle actuating motor at an end portion on the opening side,
the throttle actuating motor being set within the motor casing with extending the end cover therefrom, and
a stopper being provided in the throttle body for contacting with an outer periphery of the flange of the end cover in order to prevent rattling.
With the construction in the tenth aspect of the present invention, the throttle actuating motor can be smoothly increased into the motor casing portion in the throttle body. Furthermore, even when a gap is formed between the inner diameter on the opening side of the motor insertion opening and the outer diameter of the throttle actuating motor, rattling of the throttle actuating motor in the radial direction can be successfully prevented by contacting the outer periphery of the flange of the end cover of the throttle actuating motor projected from the motor casing portion with the inner periphery of the stoppers. It should be noted that the diameter of the motor casing on the bottom side is substantially the same as the outer diameter of the rear side of the throttle actuating motor so as not to cause rattling.
On the other hand, in the eleventh aspect of the present invention, in consideration of easiness of mounting of the throttle valve and the throttle actuating motor on the throttle body in the air intake system of the engine, there is proposed throttle apparatus for an engine comprising:
a throttle body in an air intake system of the engine;
a throttle valve and a throttle actuating motor housed in the throttle body;
a receptacle portion for receiving a gear mechanism for transmitting a driving force of the throttle actuating motor to the throttle shaft, being formed on one surface of an outer wall of the throttle body;
a gear cover covering the receptacle portion of the gear mechanism;
a receptacle casing provided on the inner surface of the gear cover for receiving a volute return spring biasing the throttle shaft in a valve closing direction;
one end of the throttle shaft being extended to the receptacle portion of the return spring of the gear cover to be coupled with the return spring at the one end.
With the construction set forth above, since the volute spring is employed as the return spring, down-sizing of the spring can be achieved. Furthermore, since the return spring is housed within the spring casing formed in the gear cover, when the gear cover is set in the throttle body, the return spring can be set simultaneously. Thus, assembling of the parts can be simplified to make assembling operation efficient.
Also, in the twelfth aspect of the present invention, in consideration of easiness of mounting of the initial opening setting mechanism, there is proposed a throttle apparatus for an engine which comprises:
a throttle body in an air intake system of the engine;
a throttle valve, a throttle actuating motor and a return spring applying a force on a throttle shaft in a throttle valve closing direction housed in the throttle body;
a throttle control system for controlling an angular position of the throttle valve by controlling the throttle actuating motor on the basis of an electric control signal; and
an initial opening setting mechanism for maintaining an initial opening of the throttle valve to be greater than a minimum opening position in a motor control within a throttle valve control range while an electric power is not supplied to the throttle actuating motor,
the initial opening setting mechanism including a lever for setting the initial opening arranged on the throttle shaft for rotation therewith, a member receiving the lever when the throttle valve is displaced in a valve closing direction up to a predetermined position and an initial opening setting spring for applying a force in a valve opening direction on the throttle shaft in order to maintain the initial opening of the throttle valve against the force of the return spring,
the lever receiving member and the initial opening setting spring being housed within a cylindrical portion provided on the wall portion of the throttle body together with an adjuster screw, the lever receiving member projecting a part from the cylindrical portion for receiving the lever, the initial opening setting spring being disposed between the lever receiving member and the adjuster screw for permitting a spring force by the adjuster screw.
In the construction set forth above, the lever may be formed with a sectorial throttle gear provided on the throttle shaft among a gear mechanism transmitting a driving force of the throttle actuating motor.
With the construction set for above, in the state where the engine key is turned OFF (electric power is not supplied to the throttle actuating motor), the lever for setting the initial opening providing on the throttle shaft contacts with the lever receiving member on the throttle body before the throttle valve is displaced to the fully closed position, by the spring force of the return spring of the throttle valve. Since the lever receiving member is preliminarily biased in the valve opening direction by the spring force of the spring for setting the initial opening. Therefore, the initial opening (initial opening greater than motor controlled minimum opening) is determined by a balance of the spring forces of the spring for setting of the initial opening and the return spring.
The initial opening can be set at arbitrary angular position by adjusting the spring force of the spring for setting the initial opening by means of the adjuster screw. On the other hand, by driving the throttle actuating motor, the lever receiving member (placed in the position depressed onto the lever of the throttle shaft) can be shifted to abut with the adjuster screw from the initial opening position against the spring force of the spring for setting the initial opening. The position where the lever receiving member contacts with the adjuster screw is the minimum mechanical opening of the throttle valve. In this sense, the adjuster screw functions as the fully closed position stopper.
The initial opening setting mechanism is constructed by only proving the lever (if the lever is integral with the throttle gear, the gear parts may be used as replacement of the parts mounted on the throttle shaft in the initial opening setting mechanism). In the throttle body, it is only required to receive the adjuster screw, the initial opening setting spring and the lever receiving member within the cylindrical portion at only one portion. Furthermore, since the adjuster screw may also be used for adjustment of spring force of the initial opening setting spring as the stopper for determining the minimum mechanical opening position of the throttle valve. Thus, number of parts can be reduced.
Also, in the thirteenth aspect of the present invention, in view of reduction of pressure loss in the air intake passage, there is proposed a throttle apparatus for an engine comprising:
a throttle body of an air intake system of the engine;
a throttle valve and a throttle actuating motor housed within the throttle body;
a throttle control system for controlling an angular position of the throttle valve by controlling driving of the throttle actuating motor on the basis of an electric control signal;
assuming that an opening is 0xc2x0 when the throttle valve is positioned to be perpendicular with an air intake passage and that an opening is 90xc2x0 when the throttle valve is positioned in parallel to an axis of the air intake passage, a movable stopper element provided on the throttle shaft being in contact with a stationary stopper element for defining a maximum opening provided on the throttle body for setting a maximum mechanical opening physically preventing further displacement of the throttle valve thereover at an angle greater than or equal to 90xc2x0, and a maximum opening of the throttle valve as controlled by the throttle actuating motor being set at 90xc2x0.
In the conventional throttle apparatus, the motor controlled maximum opening of the throttle valve is set to be smaller than 90xc2x0 (e.g. 86xc2x0). By this, even at the maximum opening as controlled by the motor, the intake air collides on the surface of the throttle valve to serve as a resistance in the air intake passage to cause the pressure loss.
In contrast to this, in the present invention, by setting the motor controlled maximum opening of the throttle valve at 90xc2x0, the throttle valve at the maximum opening position becomes substantially parallel to the intake air flow to reduce flow resistance in the air intake passage to restrict the pressure loss.
On the other hand, by setting the maximum mechanical opening over which the throttle valve cannot be driven physically for abutting the movable stopper element on the throttle shaft onto the stationary stopper element on the throttle body, to be greater than or equal to 90xc2x0, and under this condition, the maximum opening of the throttle valve as controlled by the throttle actuating motor is set at 90xc2x0 so that the motor controlled maximum opening can be set accurately without causing dimensional tolerance. Furthermore, it becomes possible to avoid collision of the movable stopper element provided on the throttle shaft and the stationary stopper element on the throttle body at the maximum opening of the throttle valve as controlling the throttle actuating motor to preventing wearing and damaging of the stopper in the long time use.